Extendable interdental brush



FIG. 1 is a front elevation view of an extendable interdental brush at a first position, wherein the toothbrush neck has been extended;

FIG. 2 is a second front elevation view of the design of FIG. 1 at a second position, wherein the toothbrush neck has been retracted;

FIG. 3 is a rear elevation view of the design of FIG. 1 at the second position;

FIG. 4 is a left side elevation view of the design of FIG. 1 at the second position;

FIG. 5 is a right side elevation view of the design of FIG. 1 at the second position;

FIG. 6 is a bottom plan view of the design of FIG. 1;

FIG. 7 is a top plan view of the design of FIG. 1;

FIG. 8 is a rear elevation view of the design of FIG. 1 at the first position;

FIG. 9 is a left side elevation view of the design of FIG. 1 at the first position;

FIG. 10 is a right side elevation view of the design of FIG. 1 at the first position;

FIG. 11 is a front, left-side perspective view of the design of FIG. 1 at the second position;

FIG. 12 is a front, left-side perspective view of the design of FIG. 1 at the first position; and,

FIG. 13 is a front, left-side perspective view of the design of FIG. 1 at a third position, wherein the interdental brush head has been extended.

The broken lines shown in the drawings represent portions of the extendable interdental brush that form no part of the claimed design. 

CLAIM The ornamental design for an extendable interdental brush, as shown and described. 